A comparative investigation of geomagnetic jerks across the SAA during the period 2000-2020

Abstract

Summary Geomagnetic field data from six magnetic observatories in and adjacent to the South Atlantic Anomaly were individually analysed to detect abrupt secular variation changes occurring on time scales of less than a year and to explore any correlation with the evolution of the South Atlantic Anomaly. After applying external field corrections by means of the CHAOS-7 model, twelve-month differences of the respective observatory monthly mean of the eastward component Y revealed evidence of several geomagnetic jerks with varying amplitudes during the period 2000-2020. These observations were compared to the CHAOS-7 spherical harmonic model and previous studies of the South Atlantic Anomaly’s evolution. It emerged from this study that global field models like CHAOS are not very effective in identifying rapid localised changes in the geomagnetic field, highlighting the importance of using observatory data in conjunction with satellite data when studying geomagnetic jerks.